(Flagyl®, Metrogel®, and Protostat® are other names for this medication.)

Use: Metronidazole is an antibiotic used to kill intestinal parasites in animals (e.g., giardia). It is also used to treat bacterial infections caused by bacteria known as anaerobes. There are two forms of this drug: metronidazole hydrochloride and metronidazole benzoate. The benzoate form is much less bitter tasting than the hydrochloride form, but benzoate may cause problems if used for very long periods in cats. 

Side Effects: Side effects reported in animals include nausea, vomiting, weakness, anemia, liver damage, blood in the urine, loss of appetite and diarrhea. Damage to the nerves is also a possible side effect and some animals will have seizures as a result. If you see your animal stumbling, knuckling over on its paws, or appearing weak, you should contact your veterinarian immediately. 

Precautions: Metronidazole makes it very difficult for the body to process alcohols. You should tell your veterinarian about any liquid medications that you give your pet and not allow your pet to ingest any alcoholic drinks while on this medication.

Directions: Dogs and cats usually receive metronidazole orally once or twice daily with food as a liquid or a tablet. Tablets should not be crushed or chewed as they have an extremely bitter taste and will cause your pet to drool and refuse more doses.

Remember: Metronidazole should be stored in a tight, light resistant, childproof container away from all children and other household pets. Oral liquids should be shaken well and stored in the refrigerator.